Air conditioning



Nov. 14, 1939. H. M. ULLSTRAND 2,179. 34

AIR CONDITIONING Filed April 13, 1958 2 Sheets-Sheet 1 MATTORNEY.

Nov. 14, 1939. ULLSTRAND 2.179.734

AIR CONDITIONING Filed April 13, 1938 2 Sheets-Sheet 2 MATTORNEY.

Patented Nov. 14, 1939.

UNITED STATES PATENT OFFICE "2,110,134 am couorrronmo Delaware Application April 13, 1938, Serial No. 301,855

8 Claims. (Cl. 62--119.5)

My invention relates to air conditioning. and more particularly to conditioning of air with a refrigeration system of the kind employing evaporation of refrigerant fluid in the presence of an inert gas or auxiliary agent.

In air conditioning the treated air may be cooled below its dew-point to effect condensation of water vapor, so that the absolute humidity of the air will be reduced. To effect such dehumidiflcation, the treated air may be conducted in thermal transfer relation with a cooling element of a refrigeration system. After dehumidiflcation, the resulting cold air is at a temperature which is too low for comfort. In order that 16 cold dehumidifled air may be employed for comfort cooling, it is necessary to increase the dry bulb temperature of treated air before introduction to the enclosure to be conditioned.

It is an object of the invention to accomplish cooling of air for dehumidification and reheating with a refrigeration system of the kind employing an inert gas or auxiliary agent, particularly to effect such cooling and reheating by fluids circulating in the refrigeration system.

Another object of the invention is to condition air in an enclosure by flowing the air past a cooling element having a gradient temperature in such a manner that air passes in heat exchange relation with successive portions of the cooling element having increasingly lower temperatures.

The above and other objects and advantagespf the invention will be more fully understood upon reference to the following description and accompanylng drawings forming a part of this specification, and of which:

Fig. 1 illustrates more or less diagrammatically air conditioning apparatus embodying the invention;

Fig. 2 more or less diagrammatically illustrates a refrigeration system and an enlarged fragmentary view of an air duct in Fig. 1 within which are disposed parts of the refrigeration system; and

.Fig. 3 is a sectional view taken on line 3-3 of Fig. 2 to illustrate more clearly the arrangement of the parts within the air duct.

In Fig. 1 a duct ll through which air is circulated is connected to an enclosure H. The

duct II is provided with a fan l2- which may be driven by a motor l2. The fan l2 draws air to be conditioned throughinlet ll, past cooling and reheating unit I! located in duct III, and discharges the conditioned air' into enclosure ll.

The path of flow of air is indicated by the arrows in Fig. 1, A duct ll is provided for exhausting or discharging air from enclome II.

The air to be conditioned may comprise fresh air or a mixture of fresh air and air discharged from enclosure ll. When the air to be conditloned is a mixture of fresh air and withdrawn air, duct connections .may be provided to vent part of the air withdrawn in duct It to the atmosphere and the remainder thereof may be mixed with fresh air and introduced at inlet ll. Other 10 arrangements may also be provided for recirculating air withdrawn from enclosure ll. Systems of this character for recirculating part of the withdrawn air form no part'of the present invention, however, since the principles of the 15 invention may be utilized in any air conditioning system in which air to be conditioned is dehumidified and. then reheated for comfort cooling.

The cooling and reheatingunit lS-forms part of an absorption refrigeration system of the kind 29 containing an inert gas or auxiliary agent. As

- shown in Fig. 2, such a system includes a generator ll, condenser l8, evaporator l8 and absorber 20. The system contains a solution of refrigerant in absorption liquid, such as ammonia 25 in water, for example, and ,also an auxiliary agent or inert gas, such as hydrogen.

The generator I1 is heated in any suitable manner, as by a gas burner 2|, for example,

whereby refrigerant vapor is expelled from solu- 30 tion in generator II. The refrigerant vapor flows upwardly through a stand-pipe 22 and a conduit-23 into an air-cooled condenser l8 where the vapor is condensed into liquid.

The condenser l8 includes an upper section Illa, an intermediate section lib, and a lower section I80, and the evaporator or cooling element l9 includes a plurality of sections l9a,' lab and llic arranged alongside each other within duct Ill. Refrigerant liquefied in upper condenser secticn Ila flows through a conduit 24 into cooling section liq. Refrigerant not liquefled in condenser section l8a flows-through'an upper looped portion of conduit 2| into intermediate condenser section l8b in which it is liquefied. Liquid refrigerant flows from intermediate condenser section lBb through conduit 25 into cooling section l9b. Refrigerant not liquefied in intermediate section l8b flows through an upper looped portion of conduit 25 into lower condenser section lie in which it is liquefied. Liquid refrigerant flows from lower condenser section I into gasseparatlng chamber 26 and thence through conduit 21 into cooling section lac.

The cooling sections Ila, Ilb and iicforming cooling element or evaporator II are disposed in the path of flow of air in duct III. These cooling sections may be provided with fins to present a relatively large heat transfer surface over which the air to be conditioned passes. Refrigerant fluid in the cooling sections evaporates and diffuses into inert gas which enters through an upper manifold 29, thereby producing a refrigerating or cooling effect. The rich gas mixture of refrigerant vapor and inert gas formed in the cooling sections flows from the lower parts thereof into a lower manifold 29 and thence through conduit 30 to absorber 29.

In absorber 20 the rich gas mixture flows counter-current to downwardly flowing weak absorption liquid which enters through a conduit 3|. The absorption liquid absorbs refrigerant vapor from the inert gas, and inert gas weak in refrigerant vapor flows from absorber 29 through a conduit 32 and upper manifold 23 into the upper parts of cooling sections l9a, I91: and I9c.

Absorption liquid enriched in refrigerant flows from the lower part of absorber 20 through a conduit 33, outer passage of a liquid heat exchanger 34, and conduit 35 into generator III. Liquid is raised in the generator by a thermosiphon tube 36 and flows back to the generator through stand-pipe 22. Refrigerant vapor expelled out of solution in generator II, together with refrigerant vapor entering through thermosiphon tube 36, flows upwardly through standpipe 22 and conduit 23 to condenser I9, as explained above.

The weakened absorption liquid from which refrigerant has been expelled flows from generator I! through conduit 31, inner passage of liquid heat exchanger 34, and conduit 3| to the upper part of absorber 20. This circulation of absorption liquid is effected by raising liquid by means of thermosiphon tube 39.

A coil 39 arranged in thermal exchange relation with absorber 20 is connected by conduits 39 and 49 to a looped coil 4| provided with cooling fins 42. The coils 38 and. 4| and connecting conduits form a secondary heat transfer system which may partly filled with a suitable volatile liquid. Evaporation of liquid in coil 38 takes up heat liberated with absorption of refrigerant vapor .in absorber 29, and condensation of vapors in coil 4I gives up heat to air flowing over the surfaces of looped coil 4i and fins 42.

-The lower end of condenser I8 is connectedby conduit 43, vessel 44 and conduit 45 to the gas circuit, as to the upper end of conduit 30, for example, so that any inert gas which may pass through the condenser can flow into the gas circuit. Refrigerant vapor not condensed in condenser I8 flows through conduit 43 to displace inert gas in vessel 44 and force gas therefrom into the gas circuit through conduit 45. By forcing gas into the gas circuit in this manner, the total pressure in the system is raised whereby an adequate condensing pressure is obtained to insure condensation of refrigerant vapor in condenser When the refigeration system is operating, inert gas circulates continuously in the gas circuit including absorber 29 and cooling element or evaporator I 9. This circulation of gas in the gas circuit is due to the difference in specific weight of the column of rich gas in cooling element I9, lower manifold 29 and conduit 39; and the column of weak gas inabsorber 20, conduit 32 and upper manifold 23. Since the rich gas is heavier than the weak gas, force is produced 'within the system for causing fiow of rich gas toward absorber'2l and flow of weak gas toward cooling sections Ila, Ilb and lie forming cooling element I9.

As illustrated most clearly in Fig. 3, the cooling sections are shown more or less diagrammatically in the form of looped coils. The lower ends of conduits 24, 23 and 21 are each connected at 49 to the upper parts of cooling sections Ila, Ilb and I9c, respectively. The lower ends of conduits 24, and 21 are U-shaped to provide liquid seals to prevent non-condensible gas from entering the cooling sections from condenser II. Since gas weak in refrigerant enters the upper parts of the cooling sections and enriched gas leaves the lower parts of the cooling sections, the gas in the lower parts of the cooling sections contains a greater amount of refrigerant vapor than the gas in the upper parts thereof. The partial vapor pressure of refrigerant in the gas is a gradient. so that the evaporating temperature of liquid refrigerant is also a gradient, the evaporating temperature of liquid being lower in the upper parts of the cooling sections.

In order to dehumidify air the dry bulb temperatue of the air must be reduced below its dew-point. Since sensible heat is removed from air to reduce the temperature thereof from a high to a lower value, a cooling element having a gradient temperature can be effectively utilized to effect cooling of the air.

In accordance with the invention. therefore, air drawn into duct I0 through inlet I4 fiows past cooling sections I9a, I9b and I90 from the high temperature parts to the low temperatue parts thereof. As air is drawn past the cooling sections it first flows over the surfaces of the lower parts of the looped coils. In the lower parts of the cooling sections I9a, I9b and I9c, rich gas is leaving through lower manifold 29 and flowing toward absorber 29. This rich gas is relatively cold and can be utilized to abstract sensible heat from air and thereby precool the same. For efllcient operation, liquid refrigerant preferably is not reaching the extreme lower portions of the cooling sections, whereby heat transfer from air to rich gas will be effected to precool the air.

The air flowing upwardly past the cooling sec tions contacts increasingly colder surfaces, and sensible heat is removed therefrom to bring the temperature of the air down to the dew-point. In the upper parts of the cooling sections at the regions where liquid refrigerant is first introduced into the presence of weak gas, the lowest temperatures prevail. In the colder upper parts of the cooling sections the air is cooled below its dew-point, and the resulting moisture condensed from the air drips from the cooling sections. The water may be collected in any suitable manner (not shown), and a drain-pipe provided for carrying away the water.

By flowing the air in the direction of increasingly colder parts of the cooling sections, the entire surface presented to the air by the cooling sections is effectively utilized to cool and dehumidify the air. With the arrangement provided the air is in counter-flow or flows countercurrent to the gas and liquid refrigerant in the cooling sections Isa, I9b and I9c. The temperature of the air flowing past the cooling sections is also a gradient, the air temperature decreasing as it flows past the cooling sections until it aim-res 3' is cooled below its dew-point. whereby moi tu is condensed out of the air. The lowwperature at the upper parts of the cooling se tions determines the resulting low temperature or the 6 cold dry air after dehumidification. The temperature of the cold dry air is too low for com-r fort, and, in order to provide conditioned air 1mcomfort cooling, it is deeirable to increase the dry bulb temperature of the air before introduclii. tion into enclosure II In accordance with the invention. sensible heat is added to the cold dry air by heat transfer from fluids in the refrigeration system. Liquid refrigerant flowing from condenser l8 and weak gas flowing from absorber are relatively warm. In order that these fluids may be utilized to reheat the dehumidifled air, the conduits in which these fluids are conducted to the cooling sections are disposed within duct ll. As shown most 90 clearly in Fig. 3, a portion of conduit 21 in which liquid refrigerantis flowing to cooling section lie is disposed within duct ill. Above the connection of conduit 21 to cooling section its at ll, the looped coil is extended upwardly to provide a portion to through which weak gas flows from upper manifold 28.

In conduit 21 and portion 9c of the looped coil, liquid refrigerant-and weak gas are flowing out of contact with each other to the upper part of cooling section Me. A refrigerating effect is produced only when liquid refrigerant flows into the presence of weak gas at 8, whereupon refrigerant evaporates and diffuses into inert gas to abstract heat from air passing over the surfaces of the cooling section.

The conduit 21 and portion 80 of the looped coil provide separate paths of flow for liquid refrigerant and weak gas within duct ill. These fluids are relatively warm and by heat transfer add sensible heat to cold dry air which has been dehumidifled. After flowing upward past the cooling section He, therefore, the dehumidifled air is reheated by passing over the surfaces of conduit 21 and pfirtion 9c of the looped coil forming '5 cooling sec on lac.

The 100 ed coils forming cooling sections I91: and lib are also provided with extreme upper coil portions 90. and 9b similar to the portion 90. Likewise, the conduits 24 and 25 through which go liquid refrigerant flows into cooling sections Na and lab are also disposed within duct Ill in a manner similar to conduit 21. To increase the effective heat radiating surface, conduits 24, 25

and 21 and portions 9a, 8b and 9c ofthe looped lg coils may be provided with heat transfer fins.

In addition to reheating dehumidifled air, the transfer of heat from warm liquid refrigerant and weak gas to the air is advantageous in that these fluids are precooled before flowing into 00 the presence of each other in the cooling sections.

Conduits 24, 25 and 21 may be arranged in thermal exchange relation with the upper portions in, 8b and 9c of the looped coils, so that precooled liquid refrigerant and precooled weak gas will 06 flow together at substantially the same low temperature. By precooling liquid refrigerant and weak gas entering the upper parts of the cooling sections, evaporation of liquid refrigerant will take place at a lower temperature in the upper 70 parts of the cooling sections.

It will be noted that conduit 30 through which rich gas flows to absorber 20 is out of thermal exchange relation with conduit 20 through which warm weak gas flows to upper manifold 28.. The

15' conduits through which warm fluid flows to the cooling sections maylieinsulated at thepcrtions outside duct II to prevent loss of heat.

Instead of arranging the cooling sections as shown'in Fig. 2, these coolingsectionsmay be arranged almost in a horizontal position and one 5 above the other in a horizontally disposed duct. with such arrangement, the overall height of. the condenser can be reduced. I

while a single embodiment of the invention has been shown and described, such variations and modiflcatiom are contemplated which fall within the true spirit and scope of the invention. as pointed out in the following claims.

What is claimed is:

l. A method of conditioning air in an enclosure with the aid of a refrigeration system employing evaporation of liquid refrigerant fluid in the presence of an auxiliary fluid at a place of cooling, which includes flowing air to the enclosure, passing such air in heat exchange relation with the place of cooling to abstract heat from said air to cool and dehumidify the same, flowing liquid refrigerant fluid and auxiliary fluid out of contact with each other to the place of cooling; and reheating said air after dehumidiflcation by transferring sensible heat thereto from liquid refrigerant fluid and auxiliary fluid before these fluids reach the place of cooling.

2. A method of conditioning air in an enclosure with the aid of a refrigerationsystem employing evaporation of liquid refrigerant fluid in the presence of. an inert gas at a place of cooling, which includes flowing air to the enclosure. passing such air in heat exchange relation with the place of cooling to abstract heat from said a air to cool and dehumidify the same, circulating the inert gas between said place of cooling and a place of absorption with the gas flowing to the place of absorption being out of thermal exchange relation with the gas flowing to the place 40 of cooling, and reheating the air after dehumidiflcation by transferring heat thereto from gas flowing from the place of absorption to ,the place of cooling.

3. A method of conditioning air in an enclosure 4.6 with the aid of a refrigeration system employing evaporation of refrigerant fluid in the presence of an inert gas at a place of cooling,'which includes flowing air to the enclosure, passing such air in heat exchange relation with the place of]. cooling to-abstract heat from said air to cool and dehumidify the same, flowing warm refrigerant fluid and auxiliary fluid'to said place of cooling, and utilizing warm fluid flowing to the place of cooling to add send-hie heat to air after dehumidiflcation and before entrance to the enclosure.

4. Apparatus f8 auditioning air in an enclosure including a omtinuous absorption refrigeration system, a duct, means for flowing air through .the duct into the enclosure, said refrigeration 0.

system including an evaporator positioned in said duct for dehumidifying air flowing therethrough, conduit means for conducting refrigerant fluid and auxiliary fluid to said evaporator for parallel flow in the latter in the presence of each other, so and said conduit means being arrangedin said duct for reheating dehumidifled air before entrance into the enclosure.

5. Apparatus for conditioning air in an enclosure including an absorption refrigeration sys- 7o tem containing auxiliary fluid, refrigerant fluid and an absorbent, a duct, means for flowing air through the duct into the enclosure, said refrigeration system including an evaporator positioned in said duct for dehumidifying air flowing 1g 4- 2,179,784 therethrough, and conduit means for separately tion refrigeration system including an evapoconducting refrigerant fluid and auxiliary fluid rator positioned in said duct ior dehumidiiying to said evaporator, said conduit means being arair flowing therethrough. a circuit including said ranged in said duct or reheating dehumidined evaporator for circulation of an inert gas, means air before entrance to the enclosure. .to conduct refrigerant fluid tosaid evaporator,

,6, Apparatus tor conditioning air in an enand means to reheat the air after dehumidincaclosure including a duct. means for flowing air tion by heat transfer Irom. gas in said gas circuit.

ULLSTRAND.

- through said duct into the enclosure, an absorp- H 

